Experimental life cycle of Lagochilascaris minor Leiper, 1909

Abstract

The life cycle of Lagochilascaris minor was studied using material collected from human lesion and applying the experimental model: rodents (mice, hamsters), and carnivorae (cats, dogs). In mice given infective eggs, orally, hatch of the third stage larvae was noted in the gut wall, with migration to liver, lungs, skeletal musculature and subcutaneous tissue becoming, soon after, encysted. In cats infected with skinned carcasses of mice (60 to 235 days of infection) it was observed: hatch of third stage larvae from the nodules (cysts) in the stomach, migration through the oesophagus, pharynx, trachea, related tissues (rhino-oropharynx), and cervical lymphonodes developing to the mature stage in any of these sites on days 9-20 post inoculation (P.I.). There was no parasite development up to the mature stage in cats inoculated orally with infective eggs, which indicates that the life cycle of this parasite includes an obligatory intermediate host. In one of the cats (fed carcass of infected mice) necropsied on day 43 P.I., it was observed the occurence of the self-infective cycle of L. minor in the lung tissues and in the cervical region which was characterized by the finding of eggs in different stages of development, third stage larvae and mature worms. It's believed that some component of the carnivorae gastrointestinal tracts may preclude the development of third stage larvae from L. minor eggs what explains the interruption of the life cycle in animals fed infective eggs. It's also pointed out the role of the intermediate host in the first stages of the life cycle of this helminth.

Avaliação da eficácia terapêutica da ivermectina sobre larvas de quarto estádio de Lagochilascaris minor em gatos infectados experimentalmente

“…No ciclo evolutivo experimental observa-se que, em camundongos inoculados com ovos infectantes do parasito, por via oral, as larvas de terceiro estádio do interior dos ovos eclodem na luz intestinal e são distribuídas para todo organismo através da circulação sistêmica, encistando-se especialmente na musculatura esquelética e tecido subcutâneo 8 . Quando gatos são alimentados com carcaças de camundongos infectados observa-se a continuidade do ciclo evolutivo do parasito.…”

“…Quando gatos são alimentados com carcaças de camundongos infectados observa-se a continuidade do ciclo evolutivo do parasito. Nestes hospedeiros, as larvas de terceiro estádio ascendem pelo trato digestivo até a orofaringe e larvas de quarto estádio são vistas do segundo ao oitavo dia, atingindo a fase adulta entre nove e quinze dias após a infecção, em tecidos da rino e orofaringe, tecido subcutâneo da região cervical, ouvido, seios nasais e face 8 .…”

Lagochilascariasis leading to severe involvement of ocular globes, ears and meninges

“…Infection with Lagochilascaris minor occurs mainly after the ingestion of third stage larvae encysted in different tissues of wild animals 5,14,22 . The larvae get rid of the cysts in the host stomach, cross the digestive wall, and by an unknown tropism mechanism, migrate to the commonly affected regions of head, neck, and thorax 5,18,22 .…”

“…The larvae get rid of the cysts in the host stomach, cross the digestive wall, and by an unknown tropism mechanism, migrate to the commonly affected regions of head, neck, and thorax 5,18,22 . The worms have a particular tropism for the cervical region, including oroand nasopharynx, mastoid, and middle ear.…”

Influence of the genetic pattern and sex of mice in experimental lagochilascariosis

“…These lesions, which can open, may contain eggs, larvae and adult worms. Clinical signs of the disease seem to depend on the number of L. minor present and tissue localization, as well as the host immune response (Fraiha et al, 1989;Campos et al, 1992). The capacity of L. minor to migrate across different human ….…”